Carbon nanotube shielding for transmission cables

ABSTRACT

A transmission cable may include a conductor core, an insulator layer surrounding the conductor core, and a shielding layer surrounding the insulator layer, wherein the shielding layer includes a carbon nanotube sheet material.

PRIORITY

This application is a continuation of U.S. Ser. No. 14/962,249 filed onDec. 8, 2015.

FIELD

The present disclosure is generally related to transmission cables and,more particularly, to a transmission cable using a carbon nanotube sheetmaterial as a shielding layer and method for making the same.

BACKGROUND

Transmission cables are used to transfer electrical power and/or datasignals. Typically, a transmission cable includes a conductor core andan insulating jacket surrounding the conductor core. The conductor corerequires good electrical conductivity in order to transmit electricalpower or data signals. The insulating jacket protects the conductor coreand fulfills other mechanical and electrical properties.

In certain applications, the cable may be exposed to various types ofelectromagnetic interference. As one example, transmission cables usedon aircraft are frequently exposed to High-Intensity Radiated Fields(“HIRF”) that emanate from high-powered radio and/or televisionfrequency transmitters, radar, satellite transmitters, large microwavecommunication systems and the like. As a result, various onboard systemsof the aircraft may be affected by the electromagnetic fields generatedby HIRF.

Accordingly, some transmission cables also include a shielding jacket(e.g., copper, silver or aluminum shielding) surrounding the insulatingjacket to protect the cable from such electromagnetic interference.Disadvantageously, such shielding increases the weight of the cablesand, thus, the overall weight of the aircraft, may be susceptible toenvironmental effects (e.g., corrosion), may generate heat in responseto the electromagnetic interference, and/or may suffer from signal decaydue to the electromagnetic interference.

Accordingly, those skilled in the art continue with research anddevelopment efforts in the field of transmission cables that areresistant to electromagnetic interference, particularly, in theaerospace industry.

SUMMARY

In one example, the disclosed cable may include a conductor core, aninsulator layer surrounding the conductor core, and a shielding layersurrounding the insulator layer, wherein the shielding layer includes acarbon nanotube sheet material.

In another example, the disclosed cable may include a conductor core,wherein the conductor core includes a carbon nanotube sheet material, aninsulator layer surrounding the conductor core, and a shielding layersurrounding the insulator layer, wherein the shielding layer includesthe carbon nanotube sheet material.

In yet another example, the disclosed method for making a cable mayinclude the steps of: (1) placing an insulator layer to surround aconductor core, and (2) placing a shielding layer to surround theinsulator layer, wherein the shielding layer includes a carbon nanotubesheet material, and wherein the carbon nanotube sheet material includescarbon nanotubes entangled together to form a network.

Other examples of the disclosed apparatus and methods will becomeapparent from the following detailed description, the accompanyingdrawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of one example of the disclosedcable;

FIG. 2 is a schematic, cross-sectional view of one example of the cableof FIG. 1;

FIG. 3 is a schematic, cross-sectional view of one example of the cableof FIG. 1;

FIG. 4 is a schematic, cutaway view of one example of the cable of FIG.1;

FIG. 5 is schematic side elevational illustration of one example of thedisclosed network of carbon nanotubes forming the carbon nanotube sheetmaterial of FIG. 1;

FIG. 6 is a schematic side elevational illustration of one example ofthe disclosed network of carbon nanotubes and thermoplastic filamentsforming the carbon nanotube sheet material of FIG. 1;

FIG. 7 is a schematic, partial top plan illustration of one example ofthe disclosed network of carbon nanotubes and thermoplastic filamentsforming the carbon nanotube sheet material of FIG. 1;

FIG. 8 is a schematic, cross-sectional view of one example of the cableof FIG. 1;

FIG. 9 is a schematic, cross-sectional view of one example of the cableof FIG. 1;

FIG. 10 is FIG. 9 is a schematic, cross-sectional view of one example ofthe cable of FIG. 1;

FIG. 11 is a schematic, cutaway view of one example of the cable of FIG.1;

FIG. 12 is a schematic, cutaway view of one example of the cable of FIG.1;

FIG. 13 is a flow diagram of one example of the disclosed method formaking the cable of FIG. 1;

FIG. 14 is a block diagram of aircraft production and servicemethodology; and

FIG. 15 is a schematic illustration of an aircraft.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawings,which illustrate specific embodiments of the disclosure. Otherembodiments having different structures and operations do not departfrom the scope of the present disclosure. Like reference numerals mayrefer to the same element or component in the different drawings.

In FIGS. 1 and 15, referred to above, solid lines, if any, connectingvarious elements and/or components may represent mechanical, electrical,fluid, optical, electromagnetic and other couplings and/or combinationsthereof. As used herein, “coupled” means associated directly as well asindirectly. For example, a member A may be directly associated with amember B, or may be indirectly associated therewith, e.g., via anothermember C. It will be understood that not all relationships among thevarious disclosed elements are necessarily represented. Accordingly,couplings other than those depicted in the block diagrams may alsoexist. Dashed lines, if any, connecting blocks designating the variouselements and/or components represent couplings similar in function andpurpose to those represented by solid lines; however, couplingsrepresented by the dashed lines may either be selectively provided ormay relate to alternative examples of the present disclosure. Likewise,elements and/or components, if any, represented with dashed lines,indicate alternative examples of the present disclosure. One or moreelements shown in solid and/or dashed lines may be omitted from aparticular example without departing from the scope of the presentdisclosure. Environmental elements, if any, are represented with dottedlines. Virtual (imaginary) elements may also be shown for clarity. Thoseskilled in the art will appreciate that some of the features illustratedin FIGS. 1 and 15 may be combined in various ways without the need toinclude other features described in FIGS. 1 and 15, other drawingfigures, and/or the accompanying disclosure, even though suchcombination or combinations are not explicitly illustrated herein.Similarly, additional features not limited to the examples presented,may be combined with some or all of the features shown and describedherein.

In FIGS. 13 and 14, referred to above, the blocks may representoperations and/or portions thereof and lines connecting the variousblocks do not imply any particular order or dependency of the operationsor portions thereof. Blocks represented by dashed lines indicatealternative operations and/or portions thereof. Dashed lines, if any,connecting the various blocks represent alternative dependencies of theoperations or portions thereof. It will be understood that not alldependencies among the various disclosed operations are necessarilyrepresented. FIGS. 13 and 14 and the accompanying disclosure describingthe operations of the method(s) set forth herein should not beinterpreted as necessarily determining a sequence in which theoperations are to be performed. Rather, although one illustrative orderis indicated, it is to be understood that the sequence of the operationsmay be modified when appropriate. Accordingly, certain operations may beperformed in a different order or simultaneously. Additionally, thoseskilled in the art will appreciate that not all operations describedneed be performed.

Unless otherwise indicated, the terms “first,” “second,” etc. are usedherein merely as labels, and are not intended to impose ordinal,positional, or hierarchical requirements on the items to which theseterms refer. Moreover, reference to a “second” item does not require orpreclude the existence of lower-numbered item (e.g., a “first” item)and/or a higher-numbered item (e.g., a “third” item).

Reference herein to “example” means that one or more feature, structure,or characteristic described in connection with the example is includedin at least one embodiment or implementation. The phrase “one example”or “another example” in various places in the specification may or maynot be referring to the same example.

Referring to FIG. 1, one example of transmission (e.g., coaxial) cable,generally designated cable 100, is disclosed. As one example, cable 100includes conductor core 102, insulator layer 104, and shielding layer106. As one non-limiting example, cable 100 is an electricaltransmission cable capable of transferring electrical power, forexample, direct current (“DC”) power. As one non-limiting example, cable100 is a data transmission cable capable of transferring data signals,for example, for communication and/or control applications.

Referring to FIGS. 2-4, and with reference to FIG. 1, conductor core 102forms an interior of cable 100. Insulator layer 104 surrounds conductorcore 102 (e.g., coaxially covers or encloses conductor core 102).Shielding layer 106 surrounds insulator layer 104 (e.g., coaxiallycovers or encloses insulator layer 104 and conductor core 102).

As one example, and as best illustrated in FIGS. 2 and 3, cable 100 mayinclude one shielding layer 106 (e.g., being formed by one or morelayers of carbon nanotube sheet material 108) (FIG. 1). As one example(not explicitly illustrated), cable 100 may include more than oneshielding layer 106 (e.g., each one of shielding layers 106 being formedby one or more layers of carbon nanotube sheet material 108). The numberof shielding layers 106 (or the number of layers of carbon nanotubesheet material 108) may depend on various factors including, but notlimited to, the desired shielding performance.

Shielding layer 106 (e.g., one or more layers of carbon nanotube sheetmaterial 108) may be wrapped or wound around insulator layer 104. As oneexample, shielding layer 106 may be manually wrapped around insulatorlayer 104. As one example, shielding layer 106 may be wrapped aroundinsulator layer 104 using an automation process. A tensile force appliedduring the wrapping process may hold shielding layer 106 in placerelative to insulator layer 104. Thus, no bonding material or agent maybe necessary at an interface of insulator layer 104 and shielding layer106 (e.g., between insulating material 110 and carbon nanotube sheetmaterial 108).

Both ends of shielding layer 106 may be grounded for HIRF protection.Connectors (not explicitly illustrated) may be connected to ends ofcable 100, for example, by crimping or soldering. The connectors maysecure conductor core 102, insulator layer 104 and shielding layer 106(and protective layer 112) together.

Referring to FIGS. 2 and 4, and with reference to FIG. 1, conductor core102 may include any suitable conductive material 114. As onenon-limiting example, conductor core 102 (e.g., conductive material 114)includes one or more flexible, conductive wires (e.g., a singleconductive wire or multiple conductive wires). As one example, the wiremay be a metal wire (e.g., a copper wire, a copper wire coated withsilver, a nickel wire coated with copper and the like), an alloy and anycombination thereof. The wire may be a solid wire (e.g., a solid-core orsingle-strand wire), a braided wire (e.g., a number of strands of wirebraided together), a stranded wire (e.g., a number of strands of wirebundled or wrapped together) and the like.

Referring to FIG. 1, and with reference to FIGS. 2 and 4, insulatorlayer 104 may include any suitable insulative material 110. Insulativematerial 110 may be an electric insulator or dielectric. As non-limitingexamples, insulator layer 104 (e.g., insulator material 110) may includeat least one of nanoclay, polytetrafluoroethylene (“PTFE”) (e.g.,Teflon), a polymer (e.g., polyethylene, polypropylene, polyimide,polyethylene propylene co-polymer, ethylene tetrafluoroethylene,fluorinated ethylene propylene,polytetrafluoroethylene/perfluoromethylvinylether co-polymer,perfluoroalkoxy polymerand and the like) and any combination thereof.Insulator layer 104 electrically insulates conductor core 102 andseparates (e.g., electrically isolates) conductor core 102 and shieldinglayer 106. Insulator layer 104 is disposed between conductor core 102and shielding layer 106, as illustrated in FIGS. 2 and 4.

Referring to FIG. 3, and with reference to FIG. 1, as one example, cable100 may also include protective layer 112 (e.g., an outer jacket).Protective layer 112 may surround shielding layer 106 (e.g., coaxiallycovers or encloses conductor core 102, insulator layer 104 and shieldinglayer 106). Shielding layer 106 may be disposed between insulator layer104 and protective layer 112, as illustrated in FIG. 3. Protective layer112 may protect cable 100 (e.g., shielding layer 106, insulator layer104 and conductor core 102) from external effects (e.g., environmentaleffects, physical damage, etc.) Protective layer 112 may include anysuitable material capable of protecting cable 100 from external effects.As non-limiting examples, protective layer 112 may include at least oneof nanoclay, PTFE, a polymer and any combination thereof.

Referring to FIG. 1, and with reference to FIGS. 2-4, as one example,shielding layer 106 includes carbon nanotube sheet material 108. Carbonnanotube sheet material 108 may serve as an effective shield againstelectromagnetic interference at high frequencies. High frequenciesinclude frequencies equal to or greater than 1 GHz. Carbon nanotubesheet material 108 may serve as an effective shield againstelectromagnetic interference at intermediate frequencies. Intermediatefrequencies include frequencies between 100 MHz and 1 GHz.

As one particular, non-limiting example, shielding layer 106 protectscable 100 from electromagnetic interference and/or radio frequencyinterference, such as interference from electromagnetic fields generatedby High-Intensity Radiated Fields (“HIRF”). In other words, shieldinglayer 106 may be configured to prevent any emission of cable 100 fromradiating beyond a shielding boundary (e.g., defined by shielding layer106) and limit other signals (e.g., electromagnetic interference) frompenetrating inside cable 100. That is, shielding layer 106 may serve asa two-way shield.

Shielding layer 106 may also serve as a secondary conductor or groundwire.

One advantage offered by using carbon nanotube sheet material 108 asshielding layer 106, for example, as compared to only a braided metalshielding as a shielding layer, is that carbon nanotube sheet material108 provides improved shielding effectiveness, for example, at higherfrequencies. Another advantage offered by using carbon nanotube sheetmaterial 108 as shielding layer 106 is that carbon nanotube sheetmaterial 108 provides for a lower overall weight of cable 100. Anotheradvantage offered by using carbon nanotube sheet material 108 asshielding layer 106 is that carbon nanotube sheet material 108 providesadditional or enhanced flexibility to cable 100. Yet another advantageoffered by using carbon nanotube sheet material 108 as shielding layer106 is that carbon nanotube sheet material 108 provides improvedcorrosion resistance to cable 100.

Relating particularly to the enhanced flexibility of cable 100 offeredby use of carbon nanotube sheet material 108 as shielding layer 106(e.g., compared to braided copper wire), generally, when a traditionalcable (e.g., data transmission or power transmission cable) with braidedcopper shielding is bent, there may be gaps or shielding breakagesformed in the braided copper shielding that may cause a reduction inshield performance. In order to enhance shield performance, a cable mayinclude two or more layers of braided copper shielding. This type ofdesign may have reduced flexibility. Shielding layer 106 formed fromcarbon nanotube sheet material 108 may offer improved flexibility suchthat cable 100 can bend in larger angles while reducing and/oreliminating the creation of gaps or breakages.

Referring to FIG. 1, and with reference to FIGS. 5-7, as one example,carbon nanotube sheet material 108 includes carbon nanotubes 118 (e.g.,a plurality of carbon nanotubes). Carbon nanotubes 118 forming carbonnanotube sheet material 108 may be discontinuous. Carbon nanotubes 118may have an extremely high aspect ratio (e.g., length to diameterratio). As one example, carbon nanotubes 118 may have a diameter rangingfrom approximately 1 nanometer to approximately 50 nanometers. As oneexample, carbon nanotubes 118 may have a length ranging fromapproximately 0.5 millimeters to approximately 4 millimeters. As oneexample, carbon nanotubes 118 may have a length ranging fromapproximately 0.5 millimeters to approximately 1 millimeter. As oneexample, carbon nanotubes 118 may have a length ranging fromapproximately 1 millimeter to approximately 4 millimeters. Othersuitable diameters and/or lengths of carbon nanotubes 118 are alsocontemplated.

Various types of carbon nanotubes 118, for example, manufactured inaccordance with known techniques, may be used to form carbon nanotubesheet material 108 (e.g., network 116 of carbon nanotubes 118). Asexamples, carbon nanotubes 118 may be single wall carbon nanotubes(“SWCNT”), multiwall carbon nanotubes (“MWCNT”), prestressed multiwallcarbon nanotubes (“PSMWCNT”), or a combination thereof. PSMWCNTs may bemade in accordance with known techniques. As one example, PSMWCNTs maybe achieved by putting MWCNTs into a bomb chamber and using an explosionto rapidly increase the pressure to force the walls of the MWCNT tocompress to within a distance where van der Waals forces dominate. Asone example, PSMWCNTs may be achieved by exposing MWCNTs to radiation toincrease pressure. In one particular, non-limiting example, PSMWNTs mayhave an interwall spacing ranging from approximately 0.22 nm toapproximately 0.28 nm (e.g., compared to approximately 0.34 nm forconventional MWCNTs). Benefits offered by PSMWNTs may include enhancedinterwall shear strengths, which in turn improve load-transfercapabilities compared to those of normal MWNTs. This provides axialtensile strength and Young's modulus that are approximately 20 percenthigher than those of normal carbon nanotubes (“CNT”).

Referring to FIGS. 5 and 7, and with reference to FIG. 1, as oneexample, carbon nanotubes 118 are entangled together to form network 116(e.g., network 116 includes or is formed of entangled carbon nanotubes118) forming carbon nanotube sheet material 108. Entanglement betweencarbon nanotubes 118 occurs at crossover locations 120 between differentones of carbon nanotubes 118. Network 116 includes a sufficient amountof carbon nanotubes 118 to provide a sufficient number of crossoverlocations 120 such that a suitable entanglement of carbon nanotubes 118is achieved to form a stable network 116.

As one example, at least some of carbon nanotubes 118 forming network116 may have varying ranges of lengths. As one example, first ones ofcarbon nanotubes 118 (identified as first carbon nanotubes 118 a in FIG.5) may have a different length or range of lengths than second ones ofcarbon nanotubes 118 (identified as second carbon nanotubes 118 b inFIG. 5). As one example, first (e.g., long) carbon nanotubes 118 a mayhave a length ranging from approximately 1 millimeter to approximately 4millimeters and second (e.g., short) carbon nanotubes 118 b may have alength ranging from approximately 0.5 millimeters to approximately 1millimeter.

Thus, and as best illustrated in FIG. 5, the use of both first carbonnanotubes 118 a (e.g., long carbon nanotubes) and second carbonnanotubes 118 b (e.g., short carbon nanotubes) may be used in forming astable network 116 of entangles carbon nanotubes 118. For example, theuse of long carbon nanotubes 118 a may increase the stability of network116 by providing a sufficient number of crossover locations 120 forshort carbon nanotubes 118 b (e.g., sufficient entanglement of carbonnanotubes 118).

Referring to FIGS. 6 and 7, and with reference to FIG. 1, as oneexample, carbon nanotube sheet material 108 also includes thermoplasticfilaments 122 (e.g., a plurality of thermoplastic filaments).Thermoplastic filaments 122 enhance the connection (e.g., entanglement)of carbon nanotubes 118. Thermoplastic filaments 122 forming carbonnanotube sheet material 108 may be discontinuous. As one example,thermoplastic filaments 122 may have a diameter of approximately 18,000nanometers. As one example, thermoplastic filaments 122 may have alength of approximately 6 millimeters.

As one example, as illustrated in FIGS. 6 and 7, carbon nanotubes 118and thermoplastic filaments 122 are entangled together to form network116 (e.g., network 116 includes or is formed of entangled carbonnanotubes 118 and thermoplastic filaments 122) forming carbon nanotubesheet material 108. Entanglement between carbon nanotubes 118 occurs atcrossover locations 120 between different ones of carbon nanotubes 118.As one example, carbon nanotubes 118 may include both long carbonnanotubes (e.g., first carbon nanotubes 118 a) and short carbonnanotubes (e.g., second carbon nanotubes 118 b), as illustrated in FIG.5. Entanglement between carbon nanotubes 118 and thermoplastic filaments122 occurs at crossover locations 124 between different ones of carbonnanotubes 118. Network 116 includes a sufficient amount of carbonnanotubes 118 and thermoplastic filaments 122 to provide a sufficientnumber of crossover locations 120 and 124 such that a suitableentanglement of carbon nanotubes 118, and carbon nanotubes 118 andthermoplastic filaments 122, is achieved to form a stable network 116(e.g., a non-woven carbon nanotube sheet material).

As illustrated in FIGS. 5-7, carbon nanotubes 118 and/or thethermoplastic filaments 122 may be randomly oriented to form network 116in carbon nanotube sheet material 108. However, alignment of carbonnanotubes 118 and/or the thermoplastic filaments 122 is alsocontemplated.

Referring to FIG. 4, as one example, carbon nanotube sheet material 108is wrapped around insulator layer 104 to form shielding layer 106. Asone example, carbon nanotube sheet material 108 is spiral wrapped (e.g.,wound) around insulator layer 104 to form shielding layer 106. In oneexample implementation, carbon nanotube sheet material 108 may be made(e.g., cut) into strips 128 of carbon nanotube sheet material 108 (e.g.,carbon nanotube tape). One or more of strips 128 of carbon nanotubesheet material 108 may be wrapped (e.g., spiral wrapped) aroundinsulator layer 104 to form shielding layer 106. Strips 128 of carbonnanotube sheet material 108 may have various dimensions suitable to wrapstrips 128 around insulator layer 104 to form shielding layer 106. Asone specific, non-limiting example, strips 128 may have a width ofapproximately 0.5 inch (12.7 millimeters). However, other widths arealso contemplated, without limitation, for example, based on aparticular application.

Referring to FIG. 8, and with reference to FIG. 1, as one example,shielding layer 106 includes multiple layers of carbon nanotube sheetmaterial 108 disposed (e.g., wrapped) around insulator layer 104. FIG. 8illustrates three layers (identified individually as first layer 108 a,second layer 108 b and third layer 108 c) of carbon nanotube sheetmaterial 108 forming shielding layer 106. However, fewer layers (e.g.,two layers) or more layers (e.g., four or more layers) of carbonnanotube sheet material 108 are also contemplated without limitation. Asone example, each layer (e.g., first layer 108 a, second layer 108 band/or third layer 108 c) of carbon nanotube sheet material 108 may beformed by wrapping (e.g., spiral wrapping) carbon nanotube sheetmaterial 108 (e.g., strips 128 of carbon nanotube sheet material 108)around insulator layer 104 and/or a preceding layer of carbon nanotubesheet material 108. For instance, multiple layers of carbon nanotubesheet material 108 may improve the shielding effectiveness of shieldinglayer 106. For example, additional layers of carbon nanotube sheetmaterial 108 may increase the attenuation (in dB) of shielding layer106.

As one example, a chemical process may be used to grow carbon nanotubes118 (e.g., long carbon nanotubes 118 a and short carbon nanotubes 118 b)on a stainless steel sheet. The grown carbon nanotubes 118 are thenscraped away from the sheet and added into water. Optionally, at thisstage, thermoplastic filaments 122 may also be added to water. Themixture of carbon nanotubes 118 (or carbon nanotubes 118 andthermoplastic filaments 122) and water may then be mixed.

In one example implementation of a process for making carbon nanotubesheet material 108, network 116 (e.g., of carbon nanotubes 118 or carbonnanotubes 118 and thermoplastic filaments 122) may be formed by pouringthe mixture of carbon nanotubes 118 (or carbon nanotubes 118 andthermoplastic filaments 122) and water over carrier material 138 (FIG.1). As examples, carrier material 138 may be a cloth, a fabric, a veil(e.g., a carbon fiber veil), a woven mat (e.g., a woven mat ofpolyethylene terephthalate (“PET”) or a woven mat of metalized PET) orthe like. Carrier material 138 may be coupled (e.g., laid on andattached) to a release film (not explicitly illustrated). As oneexample, the release film may be made of a polytetrafluoroethylene glassmaterial, such as an ARMALON™ polytetrafluoroethylene glass laminateavailable from Hi-Performance Products, Inc., of San Clemente, Calif.

As the solution is poured over carrier material 138 (and release film),carrier material 138 sifts out and holds carbon nanotubes 118 (or carbonnanotubes 118 and thermoplastic filaments 122) to form network 116 on asurface of carrier material 138. Carrier material 138 and network 116may then be passed through heating rollers to compress and bind network116 into a stable layer of entangled carbon nanotubes 118 (or carbonnanotubes 118 and thermoplastic filaments 122). The release film maythen be removed from the compressed network 116 of carbon nanotubes 118(or carbon nanotubes 118 and thermoplastic filaments 122) and carriermaterial 138 to form carbon nanotube sheet material 108.

The ratio, for example, by weight, of carbon nanotubes 118 and/orthermoplastic filaments 122 may vary depending upon the application ofcable 100. As one example, network 116 of carbon nanotubes 118 (orcarbon nanotubes 118 and thermoplastic filaments 122) may be up toapproximately ten percent by weight of carbon nanotube sheet material108. As one example, network 116 of carbon nanotubes 118 (or carbonnanotubes 118 and thermoplastic filaments 122) may be up toapproximately twenty-five percent by weight of carbon nanotube sheetmaterial 108. As one example, network 116 of carbon nanotubes 118 (orcarbon nanotubes 118 and thermoplastic filaments 122) may be up toapproximately fifty percent by weight of carbon nanotube sheet material108. As one example, network 116 of carbon nanotubes 118 (or carbonnanotubes 118 and thermoplastic filaments 122) may be more thanapproximately fifty percent by weight of carbon nanotube sheet material108.

In another example implementation of a process for making carbonnanotube sheet material 108, carbon nanotube fibers (e.g., carbonnanotubes 118) may be formed (e.g., aligned, twisted, bundled, etc.)into a thread, yarn or ribbon of carbon nanotube fibers (e.g., carbonnanotube thread, carbon nanotube yarn, or carbon nanotube ribbon). Thecarbon nanotube thread, yarn or ribbon may be woven together orotherwise combined to form carbon nanotube sheet material 108 (e.g., awoven carbon nanotube sheet material). Optionally, the carbon nanotubefibers may be impregnated into a matrix material to create apre-impregnated product. Impregnation may be modified with inclusions toenhance thermal and/or electrical properties of the carbon nanotubefibers or the carbon nanotube thread, yarn or ribbon formed from thecarbon nanotube fibers. As one non-limiting example, use of metalizedfibers may alter electrical and thermal properties while inserting, forexample, bromine molecules would alter fiber spacing affecting thermaland electrical properties, or inserting, for example, copper-basednanoparticles may improve thermal conductivity.

Referring to FIG. 9, and with reference to FIG. 1, as one example,shielding layer 106 also includes nickel coating 126. Nickel coating 126may be applied to carrier material 138. That is, carrier material 138may be coated with nickel. Nickel coating 126 may be applied to one orboth major surfaces of carrier material 138 to form each layer of carbonnanotube sheet material 108 of shielding layer 106. As one example,nickel may be applied to carrier material 138 by electroless nickelplating or electroplating. As one example, nickel may be applied tocarrier material 138 using chemical vapor deposition (“CVD”) of nickelon a continuous roll of carrier material 138 that is fed through areactor. This allows for a very small and controlled amount of nickel tobe applied to carrier material 138 and produces the nickel coatedcarrier material 138 or nickel coated carbon nanotube sheet material108.

Nickel coating 126 may serve as an effective shield againstelectromagnetic interference at low frequencies. Low frequencies includefrequencies between 0 Hz and 100 MHz.

As one example, and as illustrated in FIG. 9, nickel coating 126 appliedto carrier material 138 of carbon nanotube sheet material 108 formingshielding layer 106 may be disposed between insulator layer 104 andcarbon nanotube sheet material 108 of shielding layer 106. As oneexample (not explicitly illustrated), nickel coating 126 of shieldinglayer 106 may be disposed on an exterior of carbon nanotube sheetmaterial 108 of shielding layer 106.

While not explicitly illustrated in the example of FIG. 9, as oneexample, cable 100 may also include protective layer 112 (FIG. 3) thatsurrounds shielding layer 106 (e.g., coaxially covers or enclosesconductor core 102, insulator layer 104 and shielding layer 106).

Referring to FIG. 10, as one example, shielding layer 106 of cable 100may also include metal shielding 136. As one example, metal shielding136 may be a braided metal shielding of copper, silver or a combinationthereof. Metal shielding 136 may surround insulator layer 104 (e.g.,coaxially covers or encloses conductor core 102 and insulator layer104). Carbon nanotube sheet material 108 may surround metal shielding136 (e.g., coaxially covers or enclosed conductor core 102, insulatorlayer 104 and metal shielding 136). While not explicitly illustrated inthe example of FIG. 10, as one example, cable 100 may also includeprotective layer 112 (FIG. 3) that surrounds shielding layer 106 (e.g.,coaxially covers or encloses conductor core 102, insulator layer 104,metal shielding 136 and carbon nanotube sheet material 108).

Advantageously, the shielding effectiveness of carbon nanotube sheetmaterial 108 as shielding layer 106 of cable 100 meets or exceeds theshielding effectiveness of single or double braided silver/coppershielding, particularly at higher frequencies, with a significant weightsavings.

Referring to FIG. 11, and with reference to FIG. 1, as one example,conductor core 102 includes carbon nanotube sheet material 108 rolled orotherwise formed into roll 132. As described herein above, carbonnanotube sheet material 108 includes carbon nanotubes 118 (or carbonnanotubes 118 and thermoplastic filaments 122) entangled together toform network 116. Carbon nanotube sheet material 108 may be rolled(e.g., tightly rolled) into roll 132 (e.g., a single roll) of carbonnanotube sheet material 108 to form conductor core 102.

Referring to FIG. 12, and with reference to FIG. 1, as one example,conductor core 102 includes a plurality of rolls 132 of carbon nanotubesheet material 108. Rolls 132 of carbon nanotubes sheet material 108 maybe bundled together into bundle 134 of rolls 132 of carbon nanotubessheet material 108 to form conductor core 102.

In another example (not explicitly illustrated), conductor core 102 mayinclude both rolls 132 of carbon nanotube sheet material 108 and standsof metal wire. For instance, rolls 132 of carbon nanotube sheet material108 and stands of metal wire may be wound, wrapped, braided, orotherwise bundled together to form conductor core 102.

Carbon nanotubes 118 are good electrical conductors and also haveexcellent mechanical properties with ultra high elastic moduli. Thus,the examples illustrated in FIGS. 11 and 12 use carbon nanotube sheetmaterial 108 (either in the form of roll 132 of carbon nanotube sheetmaterial 108 or bundle 134 of rolls 132 of carbon nanotube sheetmaterial 108) to form conductor core 102. Carbon nanotube sheet material108 may be cut, trimmed, or otherwise shaped to have desired dimensions(e.g., widths and lengths) and/or shapes (e.g., strips) suitable to beformed into roll 132. As one specific, non-limiting example, carbonnanotube sheet material 108 used to form roll 132 may have a width ofapproximately 0.5 inch. However, other widths are also contemplated,without limitation, for example, depending upon a particularapplication.

In one implementation, carbon nanotube sheet material 108, for example,made in accordance with the process described above, may have a width ofapproximately fifteen inches. However, carbon nanotube sheet 108 may bemade having various other widths (e.g., less than or more than fifteeninches), without limitation. Further, carbon nanotube sheet material108, for example, made in accordance with the process described above,may be made having any length. For instance, carbon nanotube sheetmaterial 108 may be made in a continuous flow process and cut to adesired length.

Thus, the disclosed cable 100 including carbon nanotube sheet material108 as shielding layer 106 or as shielding layer 106 and conductor core102 provides several benefits over traditional braided cable shielding,particularly in the aerospace industry. As one example, carbon nanotubesheet material 108 as shielding layer 106 offers a significantly lighterand more efficient (e.g., shielding effectiveness, volumetric efficiencyand the like) cable 100. As another example, carbon nanotube sheetmaterial 108 as shielding layer 106 offers enhanced corrosionresistance, for example, against environmental conditions seen duringthe lifetime of an aircraft. As another example, carbon nanotube sheetmaterial 108 as shielding layer 106 improves the ability of cable 100 toresist the effects of interference from electromagnetic fields generatedby HIRF. As another example, carbon nanotube sheet material 108 asshielding layer 106 improves the ability of cable 100 to resist directand indirect effects of lightning strikes (e.g., improves lightningprotection).

Referring to FIG. 13, and with reference to FIGS. 1-12, one example ofdisclosed method, generally designated 200, for making cable 100, isdisclosed. Modifications, additions, or omissions may be made to method200 without departing from the scope of the present disclosure. Method200 may include more, fewer, or other steps. Additionally, steps may beperformed in any suitable order.

Referring to FIG. 13, and with reference to FIGS. 1, 2 and 4, in oneexample implementation, method 200 includes the step of providingconductor core 102, as shown at block 202. Method 200 also includes thestep of placing insulator layer 104 to surround conductor core 102, asshown at block 204. Method 200 also includes the step of placingshielding layer 106 to surround insulator layer 104, as shown at block206. As one example, shielding layer 106 includes carbon nanotube sheetmaterial 108.

Referring to FIG. 13, and with reference to FIGS. 1 and 3, in oneexample implementation, method 200 also includes the step of placingprotective layer 112 to surround shielding layer, as shown at block 208.

Referring to FIG. 13, and with reference to FIGS. 1, 2 and 4, in oneexample implementation, the step of placing shielding layer 106 tosurround insulator layer 104 (block 206) includes the step of wrappingcarbon nanotube sheet material 108 around insulator layer 104, as shownat block 210.

Referring to FIG. 13, and with reference to FIGS. 1, 2 and 4, in oneexample implementation, the step of wrapping carbon nanotube sheetmaterial 108 around insulator layer 104 (block 210) includes the step ofspiral winding strips 128 of carbon nanotube sheet material 108 aroundinsulator layer 104, as shown at block 212.

Referring to FIG. 13, and with reference to FIGS. 4 and 7, in oneexample implementation, the step of wrapping carbon nanotube sheetmaterial 108 around insulator layer 104 (block 210) also includes thestep of forming layers of carbon nanotube sheet material 108 (e.g.,strips 128 of carbon nanotube sheet material 108) around insulator layer104, as shown at block 214.

Referring to FIG. 13, and with reference to FIGS. 1, 2 and 4, in oneexample implementation, method 200 also includes the step of providingcarbon nanotube sheet material 108, as shown at block 216. As oneexample, carbon nanotube sheet material 108 forms shielding layer 106.

Referring to FIG. 13, and with reference to FIGS. 1, 2, 4, 5 and 7, inone example implementation, the step of providing carbon nanotube sheetmaterial 108 (block 216) includes the step of entangling carbonnanotubes 118 to form network 116, as shown at block 218.

Referring to FIG. 13, and with reference to FIGS. 1, 2, 4, 6 and 7, inone example implementation, the step of providing carbon nanotube sheetmaterial 108 (block 216) includes the step of entangling carbonnanotubes 118 and thermoplastic filaments 122 to form network 116, asshown at block 220.

Referring to FIGS. 1 and 8, as described above, network 116 of carbonnanotubes 118 or carbon nanotubes 118 and thermoplastic filaments 122may be formed on carrier material 138. In one example, carrier material138 may include nickel coating 126. Thus, as one example, network 116 ofcarbon nanotubes 118 (or carbon nanotubes 118 and thermoplasticfilaments 122) and carrier material 138 or carrier material 138 andnickel coating 126 form carbon nanotube sheet material 108 of shieldinglayer 106.

Referring to FIG. 13, and with reference to FIGS. 1 and 11, in oneexample implementation, the step of providing conductor core 102 (block202) includes the step of forming carbon nanotube sheet material 108into roll 132, as shown at block 224. Roll 132 of carbon nanotube sheetmaterial 108 forms conductor core 102.

Referring to FIG. 13, and with reference to FIGS. 1 and 12, in oneexample implementation, the step of providing conductor core 102 (block202) includes the step of forming bundle 134 of rolls 132 of carbonnanotube sheet material 108, as shown at block 226. Bundle 134 of rolls132 of carbon nanotube sheet material 108 forms conductor core 102.

Examples of the present disclosure may be described in the context ofaircraft manufacturing and service method 1100 as shown in FIG. 14 andaircraft 1200 as shown in FIG. 15.

During pre-production, the illustrative method 1100 may includespecification and design, as shown at block 1102, of aircraft 1200 andmaterial procurement, as shown at block 1104. During production,component and subassembly manufacturing, as shown at block 1106, andsystem integration, as shown at block 1108, of aircraft 1200 may takeplace. Thereafter, aircraft 1200 may go through certification anddelivery, as shown block 1110, to be placed in service, as shown atblock 1112. While in service, aircraft 1200 may be scheduled for routinemaintenance and service, as shown at block 1114. Routine maintenance andservice may include modification, reconfiguration, refurbishment, etc.of one or more systems of aircraft 1200.

Each of the processes of illustrative method 1100 may be performed orcarried out by a system integrator, a third party, and/or an operator(e.g., a customer). For the purposes of this description, a systemintegrator may include, without limitation, any number of aircraftmanufacturers and major-system subcontractors; a third party mayinclude, without limitation, any number of vendors, subcontractors, andsuppliers; and an operator may be an airline, leasing company, militaryentity, service organization, and so on.

As shown in FIG. 15, aircraft 1200 produced by illustrative method 1100may include airframe 1202 with a plurality of high-level systems 1204and interior 1206. Examples of high-level systems 1204 include one ormore of propulsion system 1208, electrical system 1210, hydraulic system1212 and environmental system 1214. Any number of other systems may beincluded. Although an aerospace example is shown, the principlesdisclosed herein may be applied to other industries, such as theautomotive industry, the marine industry, the construction industry orthe like.

The apparatus (cable 100) (FIG. 1) and methods (method 500) (FIG. 13)shown or described herein may be employed during any one or more of thestages of the manufacturing and service method 1100. For example,components or subassemblies corresponding to component and subassemblymanufacturing (block 1106) may be fabricated or manufactured in a mannersimilar to components or subassemblies produced while aircraft 1200 isin service (block 1112). Also, one or more examples of the apparatus,systems and methods, or combination thereof may be utilized duringproduction stages (blocks 1108 and 1110). Similarly, one or moreexamples of the apparatus and methods, or a combination thereof, may beutilized, for example and without limitation, while aircraft 1200 is inservice (block 1112) and during maintenance and service stage (block1114).

Although various examples of the disclosed transmission cable andmethods for making the same have been shown and described, modificationsmay occur to those skilled in the art upon reading the specification.The present application includes such modifications and is limited onlyby the scope of the claims.

What is claimed is:
 1. A cable comprising: a conductor core; aninsulator layer surrounding said conductor core; and a shielding layersurrounding said insulator layer, wherein said shielding layer comprisesa carbon nanotube sheet material comprising: a permeable carriermaterial formed from one of a woven fabric and a nonwoven fabric, saidcarrier material being metallized; and discontinuous carbon nanotubesentangled together to form a nonwoven network compressably coupled tosaid carrier material.
 2. The cable of claim 1 wherein said carbonnanotubes comprise a diameter ranging from approximately 1 nanometer toapproximately 50 nanometers and a length ranging from approximately 0.5millimeters to approximately 4 millimeters.
 3. The cable of claim 1wherein said carbon nanotube sheet material comprises first ones of saidcarbon nanotubes comprising a first length ranging from approximately0.5 millimeters to approximately 1 millimeter and second ones of saidcarbon nanotubes comprising a second length ranging from approximately 1millimeter to approximately 4 millimeters.
 4. The cable of claim 1wherein said carbon nanotube sheet material further comprisesdiscontinuous thermoplastic filaments entangled together and entangledwith said carbon nanotubes to form said nonwoven network coupled to saidcarrier material.
 5. The cable of claim 5 wherein said thermoplasticfilaments comprise a diameter of approximately 18,000 nanometers and alength of approximately 6 millimeters.
 6. The cable of claim 1 whereinsaid carbon nanotube sheet material is wrapped around said insulatorlayer.
 7. The cable of claim 1 wherein said shielding layer furthercomprises a plurality of strips of said carbon nanotube sheet materialspiral wound around said insulator layer.
 8. The cable of claim 1wherein said conductor core comprises a roll of said carbon nanotubesheet material.
 9. The cable of claim 8 wherein said carbon nanotubesheet material further comprises discontinuous thermoplastic filamentsentangled together and entangled with said carbon nanotubes to form saidnonwoven network coupled to said carrier material.
 10. The cable ofclaim 1 wherein said conductor core comprises a bundle of rolls of saidcarbon nanotube sheet material.
 11. The cable of claim 1 wherein saidcarrier material comprises a nonwoven carbon fiber veil.
 12. The cableof claim 1 wherein said carrier material comprises a woven polyethyleneterephthalate mat.
 13. The cable of claim 1 wherein said metallizationof said carrier layer is in contact with said insulator layer.
 14. Acable comprising: a conductor core, wherein said conductor corecomprises a carbon nanotube sheet material; an insulator layersurrounding said conductor core; and a shielding layer surrounding saidinsulator layer, wherein said shielding layer comprises said carbonnanotube sheet material; and wherein said carbon nanotube sheet materialcomprises: a permeable carrier material formed from one of a wovenfabric and a nonwoven fabric, said carrier material comprising a firstsurface and a second surface, said carrier material being metallized onsaid second surface; and discontinuous carbon nanotubes entangledtogether to form a nonwoven network compressably coupled to said firstsurface of said carrier material.
 15. The cable of claim 14 wherein saidconductor core further comprises at least one roll of said carbonnanotube sheet material.
 16. The cable of claim 14 wherein said carriermaterial comprises a nonwoven carbon fiber veil.
 17. The cable of claim14 wherein said carrier material comprises a woven polyethyleneterephthalate mat.
 18. A method for making a cable comprising: placingan insulator layer to surround a conductor core; and wrapping a carbonnanotube sheet material around said insulator layer to form a shieldinglayer surrounding said insulator layer and said conductor core, saidcarbon nanotube sheet material comprising: a permeable carrier materialformed from one of a woven fabric and a nonwoven fabric, said carriermaterial being metallized; and discontinuous carbon nanotubes entangledtogether to form a nonwoven network compressably coupled to said carriermaterial.
 19. The method of claim 18 wherein said carbon nanotube sheetmaterial further comprises discontinuous thermoplastic filamentsentangled together and entangled with said carbon nanotubes to form saidnonwoven network coupled to said carrier material.
 20. The method ofclaim 18 further comprising: forming another carbon nanotube sheetmaterial; and rolling said another carbon nanotube sheet material intoat least one roll to form said conductor core.